diff --git a/kernel/Makefile b/kernel/Makefile
index a264aed..49fdd81 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -106,6 +106,9 @@ linux_2_6_31: $(unpatch_code)
 
 linux_2_6_32: $(unpatch_code)
 
+linux_2_6_:
+	$(error No kernel source installed)
+
 do_unpatch_code:
 	echo "Un-patching source code for use with linux-2.6.14 and up ..."
 	patch -R -E -p1 < $(cur_patched)